In an attempt to determine the signal transduction pathways involved in mast cell adenosine receptor activation, microinjections of specific G protein subtype functional antibodies were made into rat basophilic leukemia cells and measurements taken of their effect on calcium mobilization using single cell calcium imaging on the confocal microscope at the NCMIR. Microinjections of antibodies to Gq, Gs, Gi2 and Gi3 were done. Results are currently being analyzed using Btrack. Preliminary results suggest that Gs and Gi2 have no effect, Gq has equivocal effects, and Gi3 may have an inhibitory effect. Observations were made that pertussis toxin inhibits the calcium responses to adenosine and plans are to study other inhibitors of adenosine receptor subtypes or other components of the signal transduction cascade. Plans are also to begin orientation on the electron microscope to study the ultrastructural changes in exocytosis in mast cells stimulated with adenosine in an attempt to create an exocytosis assay.